Atomic and subatomic particles, such as alpha particles, are constantly streaming through the universe and striking objects at random intervals. While more frequent in outer space, many of these particles exist in earth's atmosphere as well. When such a particle strikes a sensitive electronic circuit, it can generate unwanted electron-hole pairs which can upset the operation and output of the circuit. Either or both of two techniques can be used to accommodate these particles. First, the circuit can be shielded. This is not entirely satisfactory since a shield will stop only those particles having less than a certain energy level. Second, the circuit can be designed so as to compensate for the particular electrical waveform which a particle causes. This technique has not been completely satisfactory because the waveforms, which typically have rise times on the order of 5 picoseconds, are too fast to measure with today's technology.
However, there have been recent advances in devices which can sample picosecond waveforms. These devices have almost exclusively used Josephson junctions to perform the sampling and have time resolutions that today approach 2 picoseconds. So far, Josephson samplers have mostly been used to investigate electrical waveforms of circuits on the same chip and in the same cryogenic environment as the samplers. Apparatus and techniques to allow connection of a Josephson sampler to an external environment without degrading the resolution of the sampling are now being made available as sampling applications have increased.
With the advent of picosecond samplers, a controlled test environment can be established to methodically inject atomic or subatomic particles onto an electronic circuit or device. The resultant electrical waveforms produced by the bombarded electronic device can then be measured with high resolution and the electronic device can thus be re-designed for compensation. Control of the characteristics of the injected particles, such as, particle type, velocity, and angle of incidence, allows an electronic circuit or device to be tested and designed for a particular application whether in space or on earth.